OMAHA (DTN) --Given the sharp sell-off seen in soybeans Friday, it is not surprising contracts have started the CME Globex overnight session lower. Contracts are down 18 to 20 cents on follow-through selling, with additional pressure possible from more beneficial weather forecasts for South America this week. Corn and Chicago wheat contracts are 1 to 2 cents lower on spillover selling from soybeans. The U.S. dollar index is posting a modest loss early, though trade is relatively quiet.